We all know and love the moon. We're so assured that we only have one that we don't even give it a specific name. It's just The Moon. But the moon is not the Earth's only natural satellite. Here's what you need to know about 3753 Cruithne and what its weird orbit reveals about the solar system.

For some people, one moon just isn't good enough. The quest to find a second Moon has roped in Jules Verne, the man who discovered Pluto, and a pair of deluded astronomers. But here's the thing: there really is a second moon... sort of.